PHP的array_rand()不是真的随机吗？

我正在编写一些代码来随机化一系列演示文稿.相同的演示文稿不能背靠背播放.

$d数组将是演示ID的列表以及演示应在循环中播放的次数.

下面的代码工作正常,但结果并不是真正随机的.当我开始一遍又一遍地看到相同的模式时,我正在调试.看看这个输出：

ighbajafpbailgjacbiaeldiqjaphafgdjcbapSAEbjfdkcknijhbdgecaimabodalkfbgbhacbhnrjeofbdjbfhegmbpdkialmbocnliaebfaimcabchgoecbcdimgepnfjgfbfbohdahdkjgneaebha

ighbajafpbailgjacbiaeldiqjaphafgdjcbapSAEbjfdkcknijhbdgecaimabodalkfbgbhacbhnrjeofbdjbfhegmbpdkialmbocnliaebfaimcabchgoecbcdimgepnfjgfbfbohdahdkjgneaebha

这两个是分开的4分.他们是完全相同的. 4运行后,相同的字符串.另外4次运行,相同的字符串.事实上,我似乎正在按顺序获得相同的4个字符串,因为我运行它.

我的代码在下面,任何人都可以指出我可能已经产生的东西吗？如果我没有fubar任何东西,为什么“rand”所以不随机？我怎么能解决这个问题？

$d = array(
    array('a', '20'), array('b', '20'), array('c', '10'), array('d', '10'), array('e', '10'), array('f', '10'), array('g', '10'), array('h', '10'), array('i', '10'), array('j', '10'), array('k', '5'), array('l', '5'), array('m', '5'), array('n', '5'), array('o', '5'), array('p', '5'), array('q', '1'), array('r', '1'), array('s', '1'));
$out = randomizeArray($d);
//var_dump($out);

function randomizeArray ($data) {
    // Step 1: Make an array of the id's with repeats for count.
    $rarray = array();
    foreach ($data as $i => $v) {
        while ($data[$i][1] > 0) {
            array_push($rarray, $data[$i][0]);
            $data[$i][1]--;
        }
    }
    // Step 2: Randomize.
    $stat = 1;
    while ($stat == '1') {
        //echo "<br><br>Randomizing Array: <br>";
        $stat = rarr($rarray);
    }
    return $stat;
}
function rarr ($a) {
    $r = array();
    $last = "";
    while ($a) {
        $rand = array_rand($a, 1);
        // Does this value match the last one we got?
        if ($a[$rand] != $last) {
            // nope. Transfer to our $r array.
            echo $a[$rand];
            array_push($r, $a[$rand]);
            $last = $a[$rand];
            unset($a[$rand]);
        } else {
            // We have a match between our "last" presentation and the one we just selected.
            // We need to scan our array and verify that we still have different values.
            $check = $a[$rand];
            foreach ($a as $c) {
                if ($check != $c) {
                    // We have at least 2 different values in our array still.
                    // Rerun the while loop
                    continue 2;
                }
            }
            // All of the values left in our array are repeats.
            // That's no good, so return an error and rerun.
            return 1;
        }
    }
    // Everything is awesome. Return the randomized array.
    return $r;
}

解决方法:

据我所知,解决方案是在第2步之前添加：

shuffle($rarray);

它似乎解决了一些问题.重复精确47次.

如果相反,你在rarr函数中添加它：

while ($a) {
    shuffle($a);

如果将重复52次

看来它实际上是array_rand函数的问题.将array_rand更改为mt_rand,如下面的代码所示：

<?PHP
$d = array(
    array('a', '20'), array('b', '20'), array('c', '10'), array('d', '10'), array('e', '10'), array('f', '10'), array('g', '10'), array('h', '10'), array('i', '10'), array('j', '10'), array('k', '5'), array('l', '5'), array('m', '5'), array('n', '5'), array('o', '5'), array('p', '5'), array('q', '1'), array('r', '1'), array('s', '1'));

    for ($i=0; $i<10000; ++$i) {
        //ho "x";
        $out = randomizeArray($d);
        echo implode('',$out)."<br />";   
    }    


//var_dump($out);

function randomizeArray ($data) {
    // Step 1: Make an array of the id's with repeats for count.
    $rarray = array();
    foreach ($data as $i => $v) {
        while ($data[$i][1] > 0) {
            array_push($rarray, $data[$i][0]);
            $data[$i][1]--;
        }
    }
    // Step 2: Randomize.
    $stat = 1;
    while ($stat == '1') {
        //echo "<br><br>Randomizing Array: <br>";
        $stat = rarr($rarray);
    }
    return $stat;
}
function rarr ($a) {
    $r = array();
    $last = "";
    while ($a) {
        $rand = mt_rand(0,count($a)-1);
        // Does this value match the last one we got?
        if ($a[$rand] != $last) {
            // nope. Transfer to our $r array.
           // echo $a[$rand];
            array_push($r, $a[$rand]);
            $last = $a[$rand];
            unset($a[$rand]);
            $a = array_values($a);
        } else {
            // We have a match between our "last" presentation and the one we just selected.
            // We need to scan our array and verify that we still have different values.
            $check = $a[$rand];
            foreach ($a as $c) {
                if ($check != $c) {
                    // We have at least 2 different values in our array still.
                    // Rerun the while loop
                    continue 2;
                }
            }
            // All of the values left in our array are repeats.
            // That's no good, so return an error and rerun.
            return 1;
        }
    }
    // Everything is awesome. Return the randomized array.
    return $r;
}

使字符串真的很独特.

如果有人能解释它是PHP错误或“功能”,我真的很好奇